So I've been doing this for upwards of 30 years and haven't seen this one before, I'm really curious as to what others might think. This is one of those situations where things on the surface appear 100%, but something is going on somewhere that could result in a fatal issue.

First let me explain my current symptoms and then I'll give a bit of background.

I'm dealing with a 3TB SATA disk.

When connected to an external hotswap dock connected via USB to one of my PCs ("Connection A") diskpart incorrectly lists the the DISK SIZE as 746 GB. I stress disk size, because when I view the partition info on that disk it shows the partition as 2794 GB. That's right - I have a partition almost 4 times larger than the reported disk size!I used the 3rd party program "testdisk" and it reports similar.

When I use a different dock, an external enclosure ("Connection B"), everything reports correctly.

These tests were done on two different PCs.

Based on this - I would normally state that the dock ("Connection A") is faulty, and just leave it at that - but it doesn't seem quite as simple.

The main problem is that many (most) people wouldn't necessarily even use Diskpart - they would just connect the drive and initialize it via Disk Management or maybe just format it via Explorer.

Additionally, with the exception of Diskpart/Testdisk, the drive appears completely normal. I did an extended Verify test using HDDScan and a short test with SeaTools (it is a seagate drive), checked the SMART status, etc and the drive appears completely functional when using either connection.

So one would appear to be in the situation where either:a) Ignore the strangeness in DiskPart and just use the drive/connection as nothing else complains - and in fact tools meant to test the HDD specifically state it is fine.b) Blame the drive/connection and replace it.

B is obviously the safer bet - but it leaves one in the situation of not being able to trust at all how both windows and many popular HDD reporting tools verify the integrity of the drive.

For what it is worth, I'm 99% confident that the dock ("Connection A") is bad, and that diskpart/testdisk is on to something when it is reporting the incorrect disk size.

This is because I was using this dock to archive data to the drive - it has been pretty busy over the past few weeks.

The other day I attempted to move/delete some files on the drive and I started getting a windows popup about not being able to delete the file (I don't recall the exact message, but it was a less-standard "access denied" type that I hadn't really seen before).

Some quick tests of some files on the drive showed I was able to add files to the drive and read existing ones, but I was unable to delete anything (even newly created files).

I attempted to do a chkdisk and it told me my drive was of type RAW - and indeed Explorer was now reporting this as well, even though I was able to read the contents of the drive!

I thought a reboot might set things in order - and this was a big mistake. When the system came back online the drive was still RAW, yet inaccessible. Many recovery tools later I was able to recover virtually nothing on the drive (actually I could have recovered a large amount of data, but because it was split archives and many were unrecoverable and all the files were renamed, it was worthless).

I didn't keep diligent records of every step, but I do recall the symptoms I was getting when trying to use Testdisk to recover are similar to the ones I see it now giving me on what looks like an otherwise healthy drive (using "Connection A").

For now, I have removed "Connection A" (dock) and am using "Connection B" (enclosure). I'm going under the assumption that the dock is bad, but that doesn't really explain the symptoms.

I'm left extremely worried that I could get passing marks on so many tests and even windows Explorer shows the drive properly yet there could be some hidden issue that corrupts the entire drive.

If I remember rightly we had similar issues with symantec disk encryption and disks greater than 1TB.
It has to do with 4K sectors and how the USB device reports to you what is happening as opposed to Windows seeing the info and doing the maths.

Seagate disks are what we were using and they went into great detail to explain to me why the symantec software was bad and not their hardware.

If I find my notes I'll post the commands to tell you how to see it.__________________Press any key.... Yes, any key....OK, try the space bar.

Originally Posted by Wobble_WibbleIf I remember rightly we had similar issues with symantec disk encryption and disks greater than 1TB. It has to do with 4K sectors and how the USB device reports to you what is happening as opposed to Windows seeing the info and doing the maths. Seagate disks are what we were using and they went into great detail to explain to me why the symantec software was bad and not their hardware. If I find my notes I'll post the commands to tell you how to see it.

That's interesting - and I'd be interested to see what info you have - but while you might have seen similar symptoms, it doesn't sound like the root cause is the same.

Mainly - I'm not using Symantec disk encryption, or anything similar that should affect the disk in that way.

When you say 4K sector size, I'm assuming you mean disk bytes/sector as in the newer 4K sector size as opposed to the legacy 512 bytes? If that's the case, then no - this disk is a 512b sector drive as are 3 other disks in the system. I have one other external USB drive that uses the newer 4K sector size.

If you meant 4K allocation units (cluster size) - when then I really don't know how to respond as 4K allocation units are pretty default/standard for large NTFS drives and I've never really heard an issue with this.

I did do a little refresh reading on the 4K sector size and found some articles including this:

I have a feeling this article discusses some of the root issues that Symantec software had in making assumptions about 512b sector sizes on 4K disks.

As stated, this can't be my issue because I am running Windows 7 AND the disk in question is only a 512b disk. Well - technically, it is an "AF 512e" disk - but so are 2 other disks installed inside this system. My boot disk happens to be a native 512b and I have one other external USB that is native 4K.

Nevertheless, I don't see any documented issues running these disks in any combination with Vista+.

There is an interesting and disconcerting tidbit in that article though:

Quote:

Note While not stressed in the preceding table, Windows XP, Windows Server 2003, and Windows Server 2003 R2 do not support 512e or 4Kn media. While the system may boot up and be able to operate minimally, there may be unknown scenarios of functionality issues, data loss, or sub-optimal performance. Thus, Microsoft strongly cautions against using 512e media with Windows XP or other products based on the Windows XP codebase

Previously I was not aware of this. What this means is that if I tried to use this drive on a Windows 2003 system I might expect something like I am saw - namely the system boots and operates seemingly normally, but the possibility of nefarious data loss.

I suppose that the docking station I was using is either faulty due to a defect or by design. I can't honestly say that it ever worked because before now I never thought to check it and I didn't start using it as a full time solution until a couple of months ago.

There were no special drivers for this docking station - which means it would use the default Windows 7 drivers, which should have no problem reading a 512e disk. But, yes I suppose that something within the adapter hardware and how it translates to this driver could not be mapping things properly.

I just took a break from writing to check some stats on the adapter I'm using. Newegg reports that the Thermaltake ST0005U-C supports drives up to 2TB in size. However I'm not sure how solid a number that is. Honestly I've never really known an adapter to have a limit on what it will support - it seems the manufacturers usually just list the highest available capacity drives at market time so people don't wonder. But, I suppose that this adapter maybe really only can support 2TB. Even so - one would *hope* that a drive larger than that simply wouldn't format - or would only format to 2TB max rather than appear to be a properly functioning 3TB and then not operate properly.

I am getting my hand on a replacement dock (same model) tomorrow and will be able to validate further. Unfortunately I don't have a spare 2TB and additional 3TB drive on hand to test fully.

Originally Posted by donoliIIRC, there were always problems with Windows reading large drives. Do you see a difference between what's reported in a GUI & what's reported from a command prompt?

I'm aware of no issues with Windows 7+ reading 4GB and under drives.I would assume they have no problems with the larger ones either, but I've only ever tried up to 4GB.

As I explained above everything looks 100% normal from the Explorer GUI (My Computer) and also through Disk Management. The only thing that looks abnormal is what diskpart shows.

However that system has 2 other 3TB drives and another 4TB drive that all show fine from all sides.

Additionally as I stated the drive/dock combo in question was tried on another system and showed fine. Now the second system was Windows 10 which is newer than windows 7, but as per my post above anything Vista+ should have no problems with these larger capacity 512e/4K drives.

Whatever the issue ends up being it is just really disconcerting that a user can pop in a drive, format it, run tests, etc and everything is reported ok and yet some underlying addressing issue can hose your data. I'm not yet stating this is fact - it could still be the dock was just malfunctioning - and then what can you really do if your drive interface decides to screw up your drive - you're basically SOL.

Yeah it sounds like we are talking about the same thing.All my comments from the prior post still stand though because the drive in question is a 512e drive and the OS is Windows 7 - so none of that should be an issue.

Your symantec issue was software specific to how the app addressed the drive and couldn't support 4K sectors.

So the observed issues are not the same but I think the root of it is various incompatibilities with this move from 512 to 512e to 4K.

The last link you sent is interesting. For now it has convinced me that some older docks (and presumably external enclosures) will actually not be able to handle drives over 2TB. Specifically, they can't handle the 512e or 4K which is what these 3TB+ drives use.

While I was aware of some of this, I never really encountered this before and my concern has been allayed little by this.

Assuming I'm right, the replacement dock I get is going to exhibit the same problem, because it can only support 2TB.

But - instead of just not working, or showing 2 TB as the available capacity it showed the full 3TB formatted properly under windows and, at some point will corrupt the drive.I can't stress enough how disconcerting this fact is and something we should all be very vigilant about.

I will report back in the next day or two after I've tested the new dock to confirm or deny my suspicions.

Well - unfortunately BestBuy had the docking station advertised incorrectly. They stated on the website it was the one with the additional e-Sata port (which mine has USB 2.0 + eSATA) - but the one they sold me is actually *only* a USB 3.0 port.

They probably don't even make the model I have anymore as I can't seem to find one new. As my box has a copyright date of 2008 and some information I see online states 2TB max (though nothing in/on the box lists that limit) I'm going to assume that this was the root cause of my issue and I was doomed from the moment I put a 3TB drive in it.

Still...most other anecdotes that I've been reading seem to state that if your enclosure doesn't support the larger (AF) drives, then it either won't work or will just not allow you to utilize more than the 2TB.

The fact that this enclosure actually made the entire drive available as a valid 3TB partition with no indication of a problem is worrisome.

At least I have boned up on some of the specifics of these compatibility issues and I will be triple checking things like this in the future.

Ok - so I have what we will call a "final" set of tests here which would almost certainly indicate that the SATA <> USB interface in the docking station is "bad."

By "bad" I still don't know if we can call it faulty, or just bad by design (i.e. doesn't support the AF drives). Unfortunately that question can't be answered definitively because I can't get my hands on an exact model duplicate.

Either way, the way it is misbehaving I have already beaten to death as a horrible horrible thing - because almost every indication within Windows is that the drive works. It is only by looking at diskpart - and by experiencing the corruption after weeks of use was their any indication of a problem.

My last post gave me an idea, and I was able to locate a spare eSata cable which I used with the docking station to configure it with an eSata port on the same system. This way the dock is using SATA <> eSata instead of SATA <> USB. Because they undoubtedly use a different chipset for these functions I had hoped the results might be different.

As guessed - the drive appeared 100% normal to diskpart when connected via eSATA and it is only when the dock attempted to use the USB connection did they strangeness occur.

So in the end we have the following results:1) Docking station with USB (connected to standard USB 2.0 host controller) - BAD2) Docking station with USB (connected to ASMedia USB 3.0 host controller) - BAD3) Docking station with USB (connected to eSATA) - GOOD4) External USB 3.0 Disk enclosure (a different device from the dock) - GOOD

When I say GOOD, I mean diskpart shows it as such (Disk 8):

When I say BAD I mean it (Disk 8) displays as follows:

If I am to take the data/facts as I currently observe them, I think that I should feel safe using the docking station via the eSATA interface.However, due to feeling a little burned by this dock already, and the fact that I don't actually need hot-swapping on the dock right now, I am going to stick with this disk in the alternate HDD enclosure (USB 3.0).

I will report back in the coming weeks/months if I experience corruption again on this drive as that will certainly add something to this conversation.

Until then, if anyone has any comments or questions to add - please feel free.

Originally Posted by wobble_wobbleWhat do you see if you plug the disk directly into a Motherboard?

We found that the chips in the USB Drives had changed and while Windows could understand the disk, the encryption software used different techniques and didn't or couldn't understand.

I wasn't about to open up the system to test as it is an effort to get to it easily. I suspect it would work fine on the internal SATA connection as it worked fine on the eSATA.

At this point the mystery isn't why did this happen...I think it is clear that the dock didn't support anything over 2TB. The mystery/lesson is that diskpart appeared to see the drive as only 750GB, while the GUI showed it as a normal usable 3TB one.

Perhaps this is/was an oddity with my particular dock doing some weird type of unintended disk translation? Even so, I think there is a bug in Windows if Disk Management and Diskpart can't agree on the size of the disk as it exposed to the OS.

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